I am an otherwise healthy 23 year old male.Every so often, during my sleep or in the morning when I wake up, I stretch my legs a bit too far. The muscle in one or both of my calves will contract violently for about 30 seconds. Normally I have a fairly high tolerance for pain. These episodes leave me writhing in pain and sweaty afterwards. I have seen people get charlie horses in sports, but it doesn't usually too seem to cause people the same amount of pain. Also, charlie horses usually follow strenuous exercise, and my muscle contractions always occur during or immediately following sleep. For the most part Ive accepted that there is probably nothing to be done about it and that this is something I'll just have to deal with from time to time, but I would like to know how common this is.